Manufacturers of consumer vehicles (e.g., off-road vehicles, construction vehicles, cars, trucks, boats, etc.), machinery, and/or equipment having the ability to steer are looking to replace conventional mechanical steering and/or braking systems with electrical steer-by-wire systems, which are more economical, compact, and energy efficient. In steer-by-wire systems, the mechanical connection from the steering unit to the drive wheels is eliminated and replaced with an electrical solution in which drive wheels may be driven by a hydraulic system or electric actuator. In doing so, the operator may no longer feel the forces of the road, water, etc., through the steering wheel, and must operate the device without sufficient sensory information to maintain precise control of the vehicle or equipment.
To overcome the loss in sensory information from severing the mechanical linkage between the steering wheel and the drive wheels, one conventional solution includes incorporating a magneto-rheological device into the steering system. Magneto-rheological devices for damping and controlling vibration and shock are known to provide variable controlled torques or forces. Such devices may be of the “rotary-acting” or “linear-acting” variety, and may include linear dampers, rotary brakes, and rotary clutches.
In some aspects, magneto-rheological devices incorporated in tactile feedback devices include a housing containing a quantity of magneto-rheological material (e.g., a fluid or dry powder) which generally have soft-magnetic particles dispersed within, a movable member (e.g., piston or rotor) capable of moving through the magneto-rheological material to produce a magnetic field and direct a magnetic flux to desired regions of the controllable magneto-rheological material. Thus, tactile feedback devices are currently used to produce a continuously variable resistive steering torque for tactile feedback and position sensing. Torque may be increased to provide simulated end stops to limit rotational travel or number of turns.
One problem with existing tactile feedback devices is that insufficient torque is provided when systems into which the tactile feedback devices are incorporated have a constrained volume. One strategy for overcoming insufficient torque generation is to increase a diameter of the rotor(s) of the tactile feedback devices. Yet, without increasing the diameter of the overall system, there is no additional capacity available in the system to increase the diameter of individual rotors. Thus, when space and volume constraints are in place, the physical limitations prevent the ability to increase torque.
Accordingly, a need exists for improved torque generating devices, systems, and/or methods, for example, which are operable to generate an increased torque from a compact device. Improved torque generating devices, systems, and methods are advantageously less expensive, more efficient, and dimensionally smaller than commercially available devices, systems, and/or methods.